Sifting Apparatus with filter rotation and particle collection

ABSTRACT

Sifting apparatus, for sifting solid particles from a gaseous or liquid fluid, having a rotating conical filter and fan blade assembly connected to the filter exterior, both rotated together by a motor/pulley assembly, the fan blades slanted in a direction opposite the rotation direction, so that air is drawn through the filter from its interior to its exterior, having an inlet for admission of air only at the narrow end of the filter, and having a receptacle for collection of the particles at the broad end of the filter. Applications include cleaning of particle contaminants from air; cleaning beach sand by sifting out broken glass, sea weed or other debris; extraction of mineral particles from water slurry; collection of soil samples picked up by an air stream; lawn maintenance collection of weeds, leaves and burrs; biohazard removal operations; and an alternative to auger food particle transport in food processing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This present application is a continuation of U.S. patent applicationSer. No. 11/890,817, entitled “Sifting Apparatus”, which was filed onAug. 8, 2007. The disclosure of said U.S. patent application Ser. No.11/890,817 is herein incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention pertains to apparatus for sifting out solidparticles contained in a gaseous or liquid fluid, having fan or pumpingfluid impeller means for causing the fluid to flow through a filterwhich collects particles larger than the filter aperture size whileallowing smaller particles to pass with the fluid out of the apparatus.In this application the word “particle” shall mean any fragment of asolid substance, of whatever size, contained in the gaseous or liquidfluid, so as to be siftable out from the fluid by such apparatus if theparticle is larger than the filter aperture size.

There are numerous and quite varied possible applications for suchsifting apparatus, as further discussed below, including, for example,cleaning of particle contaminants from air or other gases; cleaningbeach sand by sifting out broken glass or other debris which could harmthe feet of bathers or detract from the appearance of the beach;extraction of valuable mineral particles contained in a water slurry;collection of soil samples which could be picked up by an air stream;lawn maintenance collection of weeds, leaves and burrs; radiation hazardremoval operations, such as removal of a plutonium fragment or dustspill at a nuclear facility; biohazard removal operations, such asremoval of spilled anthrax particles; an alternative to auger typetransport of food particles in food processing operations; and underseacollection of coins or other small treasure items found around ashipwreck.

The present invention may in various embodiments be useful for any suchapplications, among others, and employs an approach, detailed below,which synergistically combines two distinct physical means for siftingparticles from a fluid.

SUMMARY OF THE INVENTION

As a summary, this section of course does not explicate the invention inall the detail of the subsequent detailed description and claims. It isintended that the relative brevity of this summary shall not limit thescope of the invention, which scope is to be determined by the claims,properly construed, including all subject matter encompassed by thedoctrine of equivalents as properly applied to the claims.

In the summary and detailed description, “fluid of interest” will beused generally to denote air or any other any gaseous or liquid fluid ofinterest for use of the apparatus in sifting particles which may becontained within said fluid.

The basic approach of the present invention synergistically combines arotating filter, tapered in diameter between a narrow fluid inlet end toa broader particle collection end having a connected particle collectionreceptacle, the filter wall containing numerous filter apertures; animpeller drawing fluid of interest into the filter's fluid inlet andoutward through the filter wall, the wall stopping particles larger thanthe filter apertures, and the filter rotation causing the trappedparticles to move along the wall to the particle collection receptacle,as a result of the centrifugal force on each particle from the filterrotation, which force has a component along the surface of the filterwall in the direction of the particle collection receptacle, because ofthe tapering filter wall geometry. Thus sifting is synergisticallyaccomplished by the combination of the filtering and rotation-inducedmotion of the trapped particles into the collection receptacle.

In one broad aspect the invention comprises a filter, having a filterwall with an interior surface and an exterior surface, having aprincipal longitudinal axis and having the shape of a surface ofrevolution about said axis, said filter tapering in diameter between abroader open particle collection end and a narrower open fluid inletend, and having numerous small filter apertures extending through saidfilter wall from said interior surface of said filter wall to saidexterior surface of said filter wall;

a motor means, connected to said filter, for rotating said filter in arotation direction about said axis of said filter; a fluid impellermeans, connected to said filter, for causing said fluid of interest toflow into said fluid inlet end of said filter and to flow out of saidfilter through said filter apertures; and a particle collectionreceptacle connected to said filter at said particle collection end ofsaid filter.

In some embodiments the invention comprises the elements as describedabove in which said filter is at least substantially of the shape of afrustum of a cone extending between said fluid inlet end and saidparticle collection end.

In some embodiments the invention comprises the elements as describedabove in which said fluid impeller means comprises a rotatingcylindrical fan blade assembly surrounding and coaxial with said filter,connected to and rotating with said filter, said fan blades beingslanted in a direction opposite said rotation direction.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which all relate to the same embodiment of theinvention:

FIG. 1 is a perspective view of the fan blade assembly surrounding thecone shaped filter, with the filter position shown in phantom, forsimplicity and clarity omitting the apparatus housing shown in FIG. 2.

FIG. 2 is a side elevational sectional view of the apparatus in ahousing, through the principal axis of the filter and fan bladeassembly.

FIG. 3 is a sectional view as indicated by the lines 3-3 in FIG. 2,omitting the apparatus housing, motor and pulley belt assembly.

FIG. 4 is a sectional view as indicated by the lines 4-4 in FIG. 2, atthe intake end of the filter, omitting the housing, motor and pulleybelt assembly.

FIG. 5 is a sectional view as indicated by the lines 5-5 in FIG. 2, atthe particle collection end of the filter, omitting the housing, motorand pulley belt assembly.

FIG. 6 illustrates a portion of FIG. 2 showing the centrifugal forceacting upon a trapped particle on the filter wall, and the components ofthat force.

DETAILED DESCRIPTION

Referring now to the drawings, in which like reference numbers denotelike or corresponding elements, an embodiment designed for removal ofparticles from air as the fluid of interest is shown in FIGS. 1-6.

The apparatus has a filter 10, of the form of a frustum of a cone, openat a fluid intake end 12 and at a particle collection end 14, having afluid tight particle collection receptacle 16 connected to particlecollection end 14 of filter 10 by a fluid tight connector 18. The filterwall 20, having an interior surface 22 and an exterior surface 24, hasnumerous filter apertures 26 extending through filter wall 20,connecting interior surface 22 with exterior surface 24, which are smallenough to allow filter 10 to capture particles of interest contained inthe fluid of interest.

The filter 10 is surrounded by fan blade assembly 28, of a type commonlyknown as a squirrel cage type also commonly known as a centrifugal fan,with filter 10 and fan blade assembly 28 being coaxial and rotatablymounted on ring bearings 30, and with filter 10 and fan blade assembly28 being also securely fastened to one another by annular baffle plates32 which extend between filter 10 and fan blade assembly 28 at the endsof filter 10, so that filter 10 and fan blade assembly 28 are rotatabletogether.

Rotation of filter 10 and fan blade assembly 28 may conveniently beaccomplished by a rotation means in the form of a motor 34 and aconventional pulley belt assembly 36 connecting motor 34 to fan bladeassembly 28, as indicated in FIG. 2.

As also indicated in FIG. 2, the filter 10, fan blade assembly 28, ringbearings 30, baffle plates 32, motor 34 and pulley belt assembly 36 arecontained and supported by a housing 38.

As indicated in FIG. 3, the fan blades 39 of fan blade assembly 28 areinclined in a direction opposite to the direction 40 of rotation of thefilter 10 and fan blade assembly 28, so that the motion of fan bladeassembly 28 causes the fluid of interest to be drawn outward throughfilter 10 and fan blade assembly 28, as indicated by the fluid flowarrows 42 in FIGS. 2 and 3.

Thus the combination of motor 34, pulley belt assembly 36, and fan bladeassembly 28, constitutes a fluid impeller means, connected to filter 10,for causing fluid of interest to flow into fluid intake end 12 of filter10 and to flow out of filter 10 through filter apertures 26.

Because of baffle plates 32 extending between filter 10 and fan bladeassembly 28 at the ends of filter 10, and because of the fluid tightconnection of particle collection receptacle 16 at particle collectionend 14 of filter 10, the apparatus provides baffle means to assure thatthe operation of fan blade assembly 28 can draw fluid of interest onlyfrom the fluid intake end 12 of filter 10. Applicant believes that foroperations of practical interest in removal of particles from air, thisgeometry is necessary to allow practical operation of the unit;particularly were the baffle plates 32 to be removed, some air wouldalso be drawn in though the ends of the unit, outside exterior surface24 of filter 10 and pass out though fan blade assembly 28, without evenpassing through filter wall 20 of filter 10 so as to allow particlecollection.

The two physical processes involved in sifting particles from the fluidof interest drawn into the apparatus through rotation of fan bladeassembly 28, are best understood with reference to FIGS. 2 and 6. Theparticles 44 to be sifted from the fluid of interest initially travel onpaths parallel with the flow paths for air molecules indicated by thefluid flow arrows 42. But when the particles 44 reach interior surface22 of filter 10, the particles larger than the filter apertures 26 arestopped at interior surface 22. Because of the rotation of filter 10,particles stopped on interior surface 22 rotate with filter 10 about itsaxis 46, and are thus subject to an outward centrifugal force 48, in adirection directly outward from and perpendicular to the filter axis 46.Because of the cone shaped geometry of filter 10, the interior surface22 of filter 10 is not at right angles to this centrifugal force, but isinstead inclined at an angle to it. As is readily apparent from FIGS. 2and 6, the outward centrifugal force 48 acting on each of the capturedparticles 44 will thus have a component 50 parallel to interior surface22, in the direction of particle collection receptacle 16, as seen inFIG. 6, as well as a component 52 perpendicular to interior surface 22.The component 50 parallel to interior surface 22 will cause the capturedparticle 44 to travel along interior surface 22 into particle collectionreceptacle 16. So the path of captured particles 44, while parallel tothe gas flow path until the interior surface 22 is reached, will have asharp break, with a later portion of the path then leading alonginterior surface 22 toward particle collection receptacle 16, asindicated by the particle path arrows 54.

Thus in the above described embodiment the combination of the rotatingfilter 10, and the filter geometry, with the particle collectionreceptacle 16 connected to filter 10 at particle collection end 14,constitutes a particle collection means, for causing collection ofparticles 44 in response to centrifugal force generated by rotation offilter 10.

Applicant has had a satisfactory working prototype of the apparatusmade, in which the motor 34 is a 1 HP electric motor by MarathonElectric, of Wasau Wis., Model DQL56C7D5345 F-P, type SCS, 1725 RPM, 60hz; and in which the fan blade assembly 28 is by Indiana Fan andFabrication, and is a modified 13 3/16″ diameter Double Inlet Belt DriveBlower Wheel, Item #008507. The manner of operation of the apparatus isstraightforward.

The user positions the apparatus with fluid intake end 12 of filter 10located at a site at which it is desired to draw in fluid of interestfor sifting of particles, and commences rotation of filter 10 and fanblade assembly 28 by closing a connection by a switch (not shown) toconnect a suitable power source (not shown) to motor 34, in a mannerwell known in the art.

Some Possible Variations of Embodiments

For example, and not by way of limitation, the following variations ofembodiments from the embodiment described above and shown in thedrawings, may be suitable for various applications of the invention.

Although the filter 10 is of the form of a frustum of a cone in thedescribed and illustrated embodiment, those familiar with the art willunderstand that use of this precise geometric form is not necessary, inorder to obtain the benefit of the centrifugal force component causingthe particles 44 to move along the interior surface 22 of filter wall 20toward particle collection receptacle 16. In general the filter 10 maybe one of a form tapering in diameter between a broader open particlecollection end 14, to which particle collection receptacle 16 isconnected, and a narrower open fluid intake end 12. The form of filter10 may be that of a surface of revolution about the axis 46 of filter10.

And although the fluid motion impeller means of the illustratedembodiment is the fan blade assembly 28 which is connected to filter 10so that fan blade assembly 28 and filter 10 rotate together by theaction of motor 34 and pulley belt assembly 36, it is of course notnecessary that the invention be configured in this manner. A separatefan or other fluid motion impeller means may be employed instead, forexample a separately rotated squirrel cage fan assembly and motor. Butthe illustrated embodiment offers relative simplicity of design,manufacture and operation.

A wide variation of sizes for the filter apertures 26 of filter 10 willbe natural for differing applications of the invention. For cleaning offluids of interest, in which it is desired to achieve maximum siftingout of particulate impurities, small filter apertures 26 of the order ofmicron diameter size may be employed. But much larger filter apertures26 may be sufficient for certain other applications. For example, if onewished to clean beach sand, by sifting out and removing fragments ofbroken glass or sea shells or other debris which might hurt the feet ofbathers walking along the beach or if one wished to remove sea weedwhich might be deemed to render the beach unsightly, filter apertures 26of the order of ⅛″ or even larger might be sufficiently small, dependingupon the precise application. And if an undersea version of theinvention were to be used in treasure hunting around the wreck of aspanish galleon, e.g. to pick up gold coins that could be drawn into theapparatus by water flow caused by the impeller, apertures of ⅛″ or evenlarger might well be sufficiently small. Other possible applicationswhich may call for use of varied filter aperture size include extractionof mineral particles from water slurry; collection of soil samplespicked up by an air stream; lawn maintenance collection of weeds, leavesand burrs; radiation hazard removal operations, such as removal of aplutonium fragment or dust spill at a nuclear facility; biohazardremoval operations, such as removal of spilled anthrax particles; and analternative to auger type transport of food particles in food processingoperations.

For such applications as biohazard or radiation hazard removaloperations, use of a removable liner (not shown) within particlecollection receptacle 16 would be desirable.

Although use of the baffle plates 32 is essential or at least highlydesirable for some applications of the illustrated embodiment, to assurethat all of the fluid of interest which passes through the apparatusenters the filter 10 through fluid intake end 12 and thus passes throughfilter apertures 26 of filter 10, there may be applications of theinvention for which use of such baffling is not necessary. One advantageof the baffling is maximize sifting efficiency by having all of thefluid taken in pass through the filter. Another is to highly localizethe location from which fluid of interest is drawn, e.g. to pick upparticular targeted items. But for applications in which the apparatusis used only for general sampling of the nature of particles present inthe fluid of interest, and collection efficiency and spatial resolutionof collection are not critical, a non-baffled version of the apparatusmay suffice.

No particular form of motor 34 is required for operation of theinvention, provided said motor is sufficiently powerful to achievedesired fluid motion. An electric motor could be used, or possibly agasoline or diesel powered motor for operations away from electric powersources.

No particular material is required for construction of the invention,which may fabricated of metal, or plastics or other materials ofsuitable strength.

1. Sifting apparatus, for sifting solid particles from a fluid,comprising: (a) a filter, having a filter wall with an interior surfaceand an exterior surface, having a principal longitudinal axis between abroader open particle collection end and a narrower open fluid inletend, and having numerous small filter apertures extending through saidfilter wall from said interior surface of said filter wall to saidexterior surface of said filter wall; wherein said filter has ageometric form to cause captured particles to travel along said interiorsurface towards said particle collection end in response to rotation ofsaid filter; (b) a rotation means, connected to said filter, forrotating said filter in a rotation direction about said axis of saidfilter; and (c) a fluid impeller means, connected to said filter, forcausing said fluid to flow into said fluid inlet end of said filter andto flow out of said filter through said filter apertures; wherein saidfluid impeller means comprises a rotating cylindrical fan blade assemblysurrounding and coaxial with said filter, connected to and rotating withsaid filter, said fan blades being slanted in a direction opposite saidrotation direction;
 2. Sifting apparatus of claim 1, wherein said filteris at least substantially of the shape of a frustum of a cone extendingbetween said fluid inlet end and said particle collection end. 3.Sifting apparatus of claim 1, further comprising d) a particlecollection receptacle connected to said filter at said particlecollection end of said filter.
 4. Sifting apparatus of claim 3, whereinsaid particle collection receptacle is fluid tight and in fluid tightconnection with said filter.
 5. Sifting apparatus, for sifting solidparticles from a fluid, comprising: (a) a filter, having a filter wallwith an interior surface and an exterior surface, having a principallongitudinal axis and having the shape of a surface of revolution aboutsaid axis, said filter tapering in diameter between a broader openparticle collection end and a narrower open fluid inlet end, and havingnumerous small filter apertures extending through said filter wall fromsaid interior surface of said filter wall to said exterior surface ofsaid filter wall; (b) a rotatable cylindrical fan blade assemblysurrounding and coaxial with said filter, connected to and rotatablewith said filter in a desired rotation direction, said fan blades beingslanted in a direction opposite said rotation direction; and c) arotation means, connected to said filter and to said fan blade assembly,for rotating said filter in said rotation direction about said axis ofsaid filter;
 6. Sifting apparatus of claim 5, further comprising (d)particle collection receptacle, connected to said filter, for collectingsaid particles leaving said particle collection end of said filter;baffle means, surrounding said filter and fan blade assembly, forallowing flow of said fluid through said filter only from said fluidinlet end of said filter.
 7. Sifting apparatus, for sifting solidparticles from a fluid, comprising: (a) a filtration means, forfiltering said particles from said fluid; wherein said filtration meanscomprises a filter, having a filter wall with an interior surface and anexterior surface, having a principal longitudinal axis, said filtertapering in diameter between a broader open particle collection end anda narrower open fluid inlet end, and having numerous small filterapertures extending through said filter wall from said interior surfaceof said filter wall to said exterior surface of said filter wall (b) afluid impeller means, connected to said filtration means, for causingsaid fluid to flow through said filtration means; wherein said fluidimpeller means comprises a rotatable cylindrical fan blade assemblysurrounding and coaxial with said filter, connected to and rotatablewith said filter in a desired rotation direction, said fan blades beingslanted in a direction opposite said rotation direction; (c) a rotationmeans, for causing rotation of said filtration means; and (d) a particlecollection means, for causing collection of said particles in responseto centrifugal force generated by said rotation of said filtrationmeans, wherein said particle collection means comprises said filter anda particle collection receptacle connected to said filter at saidparticle collection end of said filter.
 8. Sifting apparatus of claim 7,wherein said filtration means has the shape of a surface of revolutionabout said axis.
 9. Sifting apparatus of claim 8, wherein said filter isat least substantially of the shape of a frustum of a cone extendingbetween said fluid inlet end and said particle collection end. 10.Sifting apparatus of claim 7, wherein said rotation means comprises amotor and a pulley belt assembly connecting said motor to saidfiltration means.
 11. Sifting apparatus of claim 1, wherein saidrotation means has an electric motor.
 12. Sifting apparatus of claim 1,wherein said rotation means has a gasoline powered motor.
 13. Siftingapparatus of claim 5, wherein said rotation means has an electric motor.14. Sifting apparatus of claim 5, wherein said rotation means has agasoline powered motor.
 15. Sifting apparatus of claim 1, wherein saidfilter apertures are at least substantially 1 micron in diameter. 16.Sifting apparatus of claim 1, wherein said filter apertures are at leastsubstantially ⅛ inch in diameter.
 17. (canceled)
 18. Sifting apparatusof claim 7, further comprising baffle means, connected to saidfiltration means and said fluid impeller means, for allowing flow ofsaid fluid through said filtration means only from a fluid inlet end ofsaid filtration means.
 19. Sifting apparatus of claim 1, wherein saidfilter is fabricated of a metal.
 20. Sifting apparatus of claim 1,wherein said filter is fabricated of plastic.
 21. Sifting apparatus ofclaim 3, further comprising baffle means, surrounding said filter andfan blade assembly, for allowing flow of said fluid through said filteronly from said fluid inlet end of said filter.